A so-called character-based presentation format has been developed for computer systems. Character-based programs and interfaces comprise a display element as an array of small squares, of which squares each can contain one character. In these character-based systems, all the information to be displayed on the display element, such as letters, numbers, spaces, and graphic symbols, are understood as characters.
At present, in graphic-based computer programs, the term ‘character’ typically denotes letters, numbers and punctuation marks. The graphic-based computer programs process the display element as a pixel matrix which consists of millions of different pixels and which pixel matrix is used to form the characters and other objects by illuminating or colouring certain pixels to constitute a desired pattern on the display element.
Irrespective of the mode of presentation, the characters must be converted to a binary code to have an intelligible meaning for the computer. In many systems, this conversion is implemented by using standardized encoding systems. Like a common language of communication, the standardized character encoding systems make it possible to transfer information and to communicate between computers and other electronic devices of various types.
There are various standardized character encoding systems. Older character-based DOS (Disk Operating System) programs use the so-called ASCII system (American Standard Code for Information Interchange). Programs based on the Windows® operating system by Microsoft use the so-called ANSI system (American National Standards Institute). WWW browsers (World Wide Web), in turn, typically use the so-called ISO Latin 1 system (International Standards Organization), whose official name is ISO-8859-1. The so-called Unicode character system has also been developed, whose official name is ISO-10646 and which attempts to cover all the existing character languages and also to present all the scientific symbols. The Unicode character system is used, for example, in the most recent Windows® operating systems.
Said character systems are known as such, and their more detailed discussion will not be necessary in this context.
Fonts refer to the external format and style for a given set of characters, for example when the characters are output on a display device or by a printer. The font defines, in addition to a given letterface style, the size and the pitch of the characters. For example, “Times New Roman” is a letterface style which defines the form of the characters using said style, but there are different fonts using the “Times New Roman” letterface style, for example in different sizes, in italics, in bold, etc. FIG. 2 shows some examples of common fonts.
Previously, due to the character-based property of computer systems, the selection of fonts has been relatively small. Typically, all the letters and symbols have been represented by simple fonts at a fixed pitch. At present, the graphic-based operating systems and applications make it possible to use a considerably larger selection of fonts. Most graphic-based operating system already include a large selection of fonts, and in addition to this, new fonts can be downloaded to be used by the operating system later on, for example in connection with the installation of a new printer.
Electronic devices, such as, for example, computers, peripheral devices, personal digital assistants (PDA), and mobile phones, typically use two different output formats for fonts: bitmap fonts and vector fonts. When bitmap fonts are used, each character is presented by using a dot matrix, and for example in the printing of a bitmap font, the printer prints out the dots included in the character. Another commonly used term for the bitmap font is the grid font. The logical size of the bitmap font is fixed, and therefore, its physical size (width×height) on the display of the electronic device or in printing depends on the resolution of the device (e.g. pixels per inch). The bitmap fonts are not as efficient as the vector fonts in view of the memory consumption, because the implementation of the bitmap fonts requires that a separate bitmap set is created for each font size in the electronic device. This is problematic particularly in language versions with a large number of characters, such as in a Chinese character set. An advantage of the bitmap fonts is their easy storability in the memory of the device and the retrieval from the memory as well as the representation of the font, because the information included in the fonts is based on bitmaps. A disadvantage of the bitmap fonts is their memory consumption, because there must be a separate font set for each font size.
Another font representation form is the so-called vector font. In vector fonts, the form of each character is geometrically defined by means of mathematical vectors. For example, the form of the character can be defined by means of successive segments in such a way that by means of them, the form of the character can be produced mathematically by adding up the sums of the vectors. In their simplest form, the segments can be straight lines with defined starting and end points. The attributes defining the appearance of the vector font do not include the size; that is, there are no separate definitions for fonts of different sizes. Because of its mathematical nature, the form of the vector font can be easily made in different sizes by scaling the starting and end coordinates of the segments defining the form, and the dimensions of the segments (length, curvature, etc). As a result, it is not necessary to store a separate font set for each font size in the electronic device, as in the case of the bitmap fonts. The vector fonts are also very suitable for electronic devices with a high resolution, where the scalability of the vector fonts does itself justice.